Fritz-Haber-Institut der Max-Planck-Gesellschaft

Abteilung Molekülphysik

Development of manipulation and trapping elements for polar molecules

An AC-trap For Polar Molecules

Polar molecules in low-field seeking states can be trapped at the minimum of a electric field. A maximum of the electric field in free space, which would allow trapping of molecules in high-field seeking states, is not allowed by Maxwell's equations. It is, on the other hand, possible to create a cylindrically symmetric geometry having a maximum in the radial direction and a minimum in the axial direction, or vice versa. Switching between these two saddle point configurations results in a field that confines molecules in both low-field and high-field seeking states.

A Molecular Synchrotron

Rather than trapping particles in a trap, as is common in atomic physics, particles can also be stored in rings. We have developed a synchrotron for low-energy neutral molecules composed of two hexapole half-rings separated by a gap. Every time the molecules pass through the gap, the electric fields are switched such as to accelerate or decelerate, and focus the molecules in the longitudinal direction.

A Molecular Fountain

Ultimately the resolution of any measurement is limited by the time a molecule spends in the measuring device. In collaboration with the Laser Centre Vrije Universiteit in Amsterdam, a molecular fountain is being set up. In this device a beam of molecules is decelerated and cooled using switched electric fields and subsequently directed upwards. The molecules will fly upwards some 30 cm before falling back under gravity, thereby passing a microwave cavity twice; as they move up and down. In this way the effective interrogation time is half a second, allowing for a very high accuracy.